What is a Master Key System?

A master key system is a set of locks that are keyed so that they each may have an individual key, called a pass key, yet all are
opened by an additional, special key called a master key. These locks would be described as keyed different and master keyed.

Within a master key system, groups of locks can be keyed alike, so that the same key operates all locks in the group, plus all
locks in the group are operated by the master key. These locks would be described as keyed alike and master keyed.

Under the master, groups of locks can be keyed different, keyed to a sub- master key, and keyed to the top master key. For
example, you might have three buildings. Each building has six locks keyed differently and a sub- master key that operates all the locks within a single building. The master key opens all the locks in all three buildings, but the
sub- master key from one building will not open any lock in either of the other two buildings.

A grand master key might be necessary if a property manager is responsible for groups of buildings, for example. Each group of
buildings would be under a separate master key, each building would have a sub- master key; and overall would be the grand master key that would open everything.

The weakness of a master key system is in the key control. If the wrong person gets a copy of the grand master key, every lock in
the system may have to be changed.

The way a master key system is laid out determines the ability that each individual key holder may have to operate any given
lock. Therefore it is best to have a clear idea of who needs to get in where before you start.

Identify the Doors

If your master key system is going to be part of new construction, use the door numbers from the architect's hardware
schedule to identify the doors. If this is an existing facility, you can assign names or numbers to the doors as you see fit. The point of this is to be able to match up a key with a door in the future, and be able to look at your
keying schedule and identify what keys open which door.

Identify the Keys

Typically locksmiths number keys in a master key system similar to this:

Great Grand Master Key: A

Grand Master key: AA

Master key: AAA

Sub- master key: AAAA

Pass or Change Key: AAAA1

If there are no sub- master keys and no grand master key, the master key would simply be numbered "A" and the
passkeys "A1", "A2", etc.

Once you have identified your doors and settled on a key numbering system, you are ready to design your master key system. At this stage a spread sheet as shown below can be a very helpful graphic organizer for your system.

Master Key

Submaster

Submaster

User key

User key

User key

User key

User key

Door No.

Location

A

AA

AB

AA1

AA2

AB1

AB2

AA3

D1

Office 1

x

x

x

D2

Office 2

x

x

x

D3

Office 3

x

x

x

D4

Office 4

x

x

x

D5

Office 5

x

x

x

Ex

Front dr.

x

x

x

In the above partial spreadsheet, key numbers are input across the top and door numbers are indicated down the left side. We see that the
master key number "A", opens all doors in the system. The "AA" sub- master key will open all doors except Office 3 and 4. The "AB" sub-
master key opens only the Office 3, 4 and the front door. Key number "AA1" opens only the Office 1, etc.

Once you have added all doors and keys to the spreadsheet you are ready to speak intelligently with your locksmith about how you need your
system to work.